diff --git a/git-gui.sh b/git-gui.sh
index c5f1329932..f87c12ea88 100755
--- a/git-gui.sh
+++ b/git-gui.sh
@@ -1262,6 +1262,7 @@ proc apply_config {} {
 	}
 }
 
+set default_config(merge.diffstat) true
 set default_config(merge.summary) false
 set default_config(merge.verbosity) 2
 set default_config(user.name) {}
diff --git a/lib/option.tcl b/lib/option.tcl
index 9f76f0294e..4924b9aa56 100644
--- a/lib/option.tcl
+++ b/lib/option.tcl
@@ -184,6 +184,7 @@ proc do_options {} {
 
 		{b merge.summary {Summarize Merge Commits}}
 		{i-1..5 merge.verbosity {Merge Verbosity}}
+		{b merge.diffstat {Show Diffstat After Merge}}
 
 		{b gui.trustmtime  {Trust File Modification Timestamps}}
 		{b gui.pruneduringfetch {Prune Tracking Branches During Fetch}}